diff --git a/CHANGELOG b/CHANGELOG
index f81f36c7f5..48e93c0e12 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Update model 303 to new format
+
 Version 5.0.0 - 2018-10-01
 * Bug fixes (see mercurial logs for details)
 * Allow to export tax reports as file
diff --git a/aeat303.txt b/aeat303.txt
index 42dcd3824d..8c587ca11e 100644
--- a/aeat303.txt
+++ b/aeat303.txt
@@ -1 +1 @@
-<T3030${year}${period}0000><AUX>${justify('', 300)}</AUX><T30301000> ${declaration_type}${company.party.tax_identifier.code[2:]}${justify(company.rec_name.upper(), 80)}${year}${period}2322         2222${format_decimal(amounts['01'])}${format_percentage(amounts['02'])}${format_decimal(amounts['03'])}${format_decimal(amounts['04'])}${format_percentage(amounts['05'])}${format_decimal(amounts['06'])}${format_decimal(amounts['07'])}${format_percentage(amounts['08'])}${format_decimal(amounts['09'])}${format_decimal(amounts['10'])}${format_decimal(amounts['11'])}${format_decimal(amounts['12'])}${format_decimal(amounts['13'])}${format_decimal(amounts['14'])}${format_decimal(amounts['15'])}${format_decimal(amounts['16'])}${format_percentage(amounts['017'])}${format_decimal(amounts['18'])}${format_decimal(amounts['19'])}${format_percentage(amounts['20'])}${format_decimal(amounts['21'])}${format_decimal(amounts['22'])}${format_percentage(amounts['23'])}${format_decimal(amounts['24'])}${format_decimal(amounts['25'], True)}${format_decimal(amounts['26'], True)}${format_decimal(amounts['27'], True)}${format_decimal(amounts['28'])}${format_decimal(amounts['29'])}${format_decimal(amounts['30'])}${format_decimal(amounts['31'])}${format_decimal(amounts['32'])}${format_decimal(amounts['33'])}${format_decimal(amounts['34'])}${format_decimal(amounts['35'])}${format_decimal(amounts['36'])}${format_decimal(amounts['37'])}${format_decimal(amounts['38'])}${format_decimal(amounts['39'])}${format_decimal(amounts['40'], True)}${format_decimal(amounts['41'], True)}${format_decimal(amounts['42'], True)}${format_decimal(amounts['43'], True)}${format_decimal(amounts['44'], True)}${format_decimal(amounts['45'], True)}${format_decimal(amounts['46'], True)}022${justify('', 592)}</T30301000><T30303000>${format_decimal(amounts['59'])}${format_decimal(amounts['60'])}${format_decimal(amounts['61'])}${format_decimal(amounts['62'])}${format_decimal(amounts['63'])}${format_decimal(amounts['74'])}${format_decimal(amounts['75'])}${format_decimal(amounts['76'])}${format_decimal(amounts['64'], True)}${format_percentage(amounts['65'])}0000${format_decimal(amounts['66'], True)}${format_decimal(amounts['77'])}${format_decimal(amounts['67'])}${format_decimal(amounts['68'], True)}${format_decimal(amounts['69'], True)}${format_decimal(amounts['70'], True)}${format_decimal(amounts['71'], True)}${justify('', 60)}0    0    0    0    0    0     ${format_decimal(amounts['80'])}${format_decimal(amounts['81'])}${format_decimal(amounts['93'])}${format_decimal(amounts['83'])}${format_decimal(amounts['84'])}${format_decimal(amounts['85'])}${format_decimal(amounts['86'])}${format_decimal(amounts['79'])}${format_decimal(amounts['88'])}0${format_percentage(amounts['89'])}${format_percentage(amounts['90'])}${format_percentage(amounts['91'])}${format_percentage(amounts['92'])}${format_decimal(amounts['94'])}${format_decimal(amounts['95'])}${format_decimal(amounts['96'])}${format_decimal(amounts['97'])}${format_decimal(amounts['98'])}${format_decimal(amounts['99'])}${justify('', 468)}</T30303000></T3030${year}${period}0000>
+<T3030${year}${period}0000><AUX>${justify('', 300)}</AUX><T30301000> ${declaration_type}${company.party.tax_identifier.code[2:]}${justify(company.rec_name.upper(), 80)}${year}${period}2322         2222${format_decimal(amounts['01'])}${format_percentage(amounts['02'])}${format_decimal(amounts['03'])}${format_decimal(amounts['04'])}${format_percentage(amounts['05'])}${format_decimal(amounts['06'])}${format_decimal(amounts['07'])}${format_percentage(amounts['08'])}${format_decimal(amounts['09'])}${format_decimal(amounts['10'])}${format_decimal(amounts['11'])}${format_decimal(amounts['12'])}${format_decimal(amounts['13'])}${format_decimal(amounts['14'])}${format_decimal(amounts['15'])}${format_decimal(amounts['16'])}${format_percentage(amounts['017'])}${format_decimal(amounts['18'])}${format_decimal(amounts['19'])}${format_percentage(amounts['20'])}${format_decimal(amounts['21'])}${format_decimal(amounts['22'])}${format_percentage(amounts['23'])}${format_decimal(amounts['24'])}${format_decimal(amounts['25'], True)}${format_decimal(amounts['26'], True)}${format_decimal(amounts['27'], True)}${format_decimal(amounts['28'])}${format_decimal(amounts['29'])}${format_decimal(amounts['30'])}${format_decimal(amounts['31'])}${format_decimal(amounts['32'])}${format_decimal(amounts['33'])}${format_decimal(amounts['34'])}${format_decimal(amounts['35'])}${format_decimal(amounts['36'])}${format_decimal(amounts['37'])}${format_decimal(amounts['38'])}${format_decimal(amounts['39'])}${format_decimal(amounts['40'], True)}${format_decimal(amounts['41'], True)}${format_decimal(amounts['42'], True)}${format_decimal(amounts['43'], True)}${format_decimal(amounts['44'], True)}${format_decimal(amounts['45'], True)}${format_decimal(amounts['46'], True)}022${'2' if period in ['4T', '12'] else '0'}${justify('', 591)}</T30301000><T30303000>${format_decimal(amounts['59'])}${format_decimal(amounts['60'])}${format_decimal(amounts['61'])}${format_decimal(amounts['62'])}${format_decimal(amounts['63'])}${format_decimal(amounts['74'])}${format_decimal(amounts['75'])}${format_decimal(amounts['76'])}${format_decimal(amounts['64'], True)}${format_percentage(amounts['65'])}0000${format_decimal(amounts['66'], True)}${format_decimal(amounts['77'])}${format_decimal(amounts['67'])}${format_decimal(amounts['68'], True)}${format_decimal(amounts['69'], True)}${format_decimal(amounts['70'], True)}${format_decimal(amounts['71'], True)}${justify('', 60)}0    0    0    0    0    0     ${format_decimal(amounts['80'])}${format_decimal(amounts['81'])}${format_decimal(amounts['93'])}${format_decimal(amounts['83'])}${format_decimal(amounts['84'])}${format_decimal(amounts['85'])}${format_decimal(amounts['86'])}${format_decimal(amounts['79'])}${format_decimal(amounts['88'])}0${format_percentage(amounts['89'])}${format_percentage(amounts['90'])}${format_percentage(amounts['91'])}${format_percentage(amounts['92'])}${format_decimal(amounts['94'])}${format_decimal(amounts['95'])}${format_decimal(amounts['96'])}${format_decimal(amounts['97'])}${format_decimal(amounts['98'])}${format_decimal(amounts['99'])}${format_percentage(amounts['107'])}${justify('', 463)}</T30303000></T3030${year}${period}0000>
diff --git a/tests/303.txt b/tests/303.txt
index 03ba10e37f..93e2235b04 100644
--- a/tests/303.txt
+++ b/tests/303.txt
@@ -1 +1 @@
-<T30302018010000><AUX>                                                                                                                                                                                                                                                                                                            </AUX><T30301000> IB01000009DUNDER MIFFLIN                                                                  2018012322         222200000000000000000004000000000000000000000000000000000000010000000000000000000000000000000020000021000000000000000420000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001400000000000000000000000000000000000000500000000000000000000000000000000000000000000000000000000000000000420000000000000010000000000000000021000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000210000000000000002100022                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                </T30301000><T30303000>00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000210010000000000000000000002100000000000000000000000000000000000000000000000000000000000000000021000000000000000000000000000000002100                                                            0    0    0    0    0    0     000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    </T30303000></T30302018010000>
+<T30302018010000><AUX>                                                                                                                                                                                                                                                                                                            </AUX><T30301000> IB01000009DUNDER MIFFLIN                                                                  2018012322         2222000000000000000000040000000000000000000000000000000000000100000000000000000000000000000000200000210000000000000004200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000014000000000000000000000000000000000000005000000000000000000000000000000000000000000000000000000000000000004200000000000000100000000000000000210000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002100000000000000021000220                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               </T30301000><T30303000>00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000210010000000000000000000002100000000000000000000000000000000000000000000000000000000000000000021000000000000000000000000000000002100                                                            0    0    0    0    0    0     00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000                                                                                                                                                                                                                                                                                                                                                                                                                                                                               </T30303000></T30302018010000>